Shielded electrical connectors are used to provide connections between electrical circuits through an interface that is free from electromagnetic interference. In connectors through which signals flow in and out of the interface with a mating connector, such as input/output connectors, shielding is especially important to maintain signal integrity. The Universal Serial Bus (USB) connector is an advanced shielded connector that can be serially integrated together with various such input/output connectors.
FIG. 1 shows a conventional USB connector 1, which generally comprises an insulating case 2 and a plurality of terminals 3. The insulating case 2 further comprises a terminal projection 22 extending upwardly from a bottom wall 24. The bottom wall includes terminal cavities 221 that extend upwardly along the terminal projection in terminal grooves 2211. A cap 223 at the end of the end of the terminal grooves includes lip portions 2231 which define terminal recesses 2223. The terminal projection 22 and side walls 21 of the case define an annular slot 23 for receiving a portion of a mating connector (not shown) therein.
Terminals 3 are loaded through the terminal cavities 221 into terminal grooves 2211. As shown in FIGS. 2 and 3, the contacts 3 are stamped and formed to have a contact portion 31 that includes a bent portion 32, a retention portion 34, an insertion portion 35 and an end portion 36. The contact portion defines a contact point 311. The bent portion 32 is connected to the retention portion at transition point 312. The contact portion 31 protrudes out of the terminal grooves 2211 into the slot 23 to engage terminals of a mating connector. The insertion portion 35 extends out of the bottom wall of the case 2, so that it can be fixed to the circuit board 5. The terminals 3 are inserted into the terminal grooves 2211 in the case 2 with the end portions 36 entering recesses 2223 and are retained therein. A retention portion 34 has barbs 341 for skiving into the walls of the terminal cavities to retain the terminals within the case 2.
The conventional shielded connector presents the following disadvantages. The elastic engagement force of the terminal 3 provided by the transition point 312 can be inadequate. When the terminal 2 provides inadequate engagement force, the signal transmission effect of contact 3 is not satisfactory. Accordingly, the length L.sub.1 of the bent portion 32 must be sufficiently large to provide the contact portion with the necessary engagement force. Therefore, the length L.sub.2 of the retention portion is sacrificed, diminishing its retention capacity. To ensure adequate retention capacity, the height H.sub.2 of the insulative case 2 cannot be reduced. Therefore, the overall height H.sub.1 of the connector must be greater to provide adequate engagement force and retention capacity.
Additionally, assembly of the contact 3 is cumbersome because the free end portion 36 must be inserted into recesses 2223 within lip portions 2231.
Moreover, although not shown in FIG. 1, shielded connectors such as USB connectors often have panel engaging members extending from the mating surface of the shield 4. Such panel engaging fingers often extend forwardly and outwardly to making the connector more bulky and difficult to handle.
Therefore, an object of the present invention is to provide a shielded connector with a terminal structure that is easy to load and provides sufficient engagement force and retention capacity while minimizing the overall height of the connector.
It is also an object of the present invention to provide a shielded electrical connector with panel engaging fingers which are easily compacted with other such shielded connectors.